Roller mill

ABSTRACT

The invention relates to a roller mill having at least one mill roller and a rotatable mill platen, which are arranged in a mill inner space, and a moment arm which is retained so as to be pivotably movable and rotationally secure in a bearing, with the mill roller being supported in a rotatable manner at one end of the moment arm and there further being provided means for applying a force to the moment arm comprising a pressure cylinder which is in operative contact with the moment arm in order to adjust the mill pressure which is applied by the mill roller. The contact location, at which the force of the pressure cylinder is transmitted to the moment arm, is located outside the mill inner space.

The invention relates to a roller mill having at least one mill rollerand a rotatable mill platen.

In practice, extremely different configurations of roller mills areknown. In one configuration, the mill roller is secured to one end of arotatable shaft which is retained outside the mill in a spherical rollerbearing. In another configuration, a moment arm is provided and isretained so as to be pivotably movable and rotationally secure in abearing, the mill roller being supported rotatably at one end of themoment arm. There are further provided means for applying a force to themoment arm in order to adjust the pressure which is applied by the millroller. The means for applying a force to the moment arm are formed byresilient elements in many applications. In order better to be able tovary the mill pressure and also to be able to adjust relatively largemill pressures, however, hydraulic cylinders are used in many cases.

In JP-A-2002 159 874, that hydraulic cylinder is formed by a tensioncylinder which is supported in an articulated manner and which isconnected to the moment arm in an articulated manner.

JP-A-2000 312 832 further discloses a coal mill, wherein the moment armis operatively connected to a pressure cylinder in order to adjust thepressure which is applied by the mill roller. The cylinder is mounted onthe housing wall so as to be fixed in position so that the cylinderpiston protrudes into the mill inner space and, at that location,transmits the force to the moment arm via a pad which is guided in asleeve. Since the moment arm is supported in a pivotably movable manner,powerful transverse forces which have to be taken up by the sleeve occurin the region of the contact location.

The problem addressed by the invention is to find a new construction forintroducing a force into the moment arm.

This problem is solved according to the invention by the features ofclaim 1.

The roller mill according to the invention substantially comprises atleast one mill roller and a rotatable mill platen, which are arranged ina mill inner space, and a moment arm which is retained so as to bepivotably movable and rotationally secure in a bearing, with the millroller being supported in a rotatable manner at one end of the momentarm and there further being provided means for applying a force to themoment arm comprising a pressure cylinder which is in operative contactwith the moment arm in order to adjust the mill pressure which isapplied by the mill roller. The contact location, at which the force ofthe pressure cylinder is transmitted to the moment arm, is locatedoutside the mill inner space.

A pressure cylinder can be constructed so as to be smaller and morecompact in comparison with a tension cylinder, whereby installationspace is reduced. A contact location which is arranged outside the millinner space further has the advantage that it is subject to less wearbecause no dust and no high temperatures are present at that location.

The dependent claims relate to other constructions of the invention.

According to a preferred configuration, the pressure cylinder isarranged so as to be fixed in position. A fixed cylinder is firstly morecompact, and reduces the movable masses of a roller unit which has afavourable effect with regard to vibrations.

The pressure cylinder is further advantageously orientatedperpendicularly relative to the connection between the bearing and themill roller, whereby it is possible to have optimum force transmission.The pressure cylinder is further preferably arranged in a central regionbetween the mill roller and the bearing.

According to a preferred construction of the invention, there isprovided between the pressure cylinder and the moment arm at least onepressure bearing which allows relative movement between the pressurecylinder and the moment arm. That pressure bearing can particularly havea first pressure face and a second pressure face in order to apply asliding movement, with the friction coefficient preferably being lessthan 0.2. The relative movement between the fixed pressure cylinder andthe pivotably movable moment arm can be compensated for by the pressurebearing to such an extent that the transverse forces which act on thepressure cylinder are minimised. In another construction of theinvention, a third pressure face and a fourth pressure face are furtherprovided in order to apply a pivoting movement in order to furtherminimise the transverse forces in that manner. By the pressure bearingbeing arranged outside the mill inner space, complex sealing of thebearing is unnecessary.

Further advantages and constructions of the invention will be explainedin greater detail below with reference to the description and thedrawings, in which:

FIG. 1 is a partial sectioned view of the roller mill,

FIG. 2 is a schematic illustration of the roller mill,

FIG. 3 is a partial sectioned view in the region of the contact locationat which the force of the pressure cylinder is transmitted to the momentarm.

The roller mill illustrated in FIG. 1 substantially comprises a millroller 1 and a rotatable mill platen 2 which are arranged in a millinner space 4 which is delimited by a housing 3. A moment arm 5 isfurther provided and is retained so as to be pivotably movable androtationally secure in a bearing 6 which is constructed as a fixedbearing, with the mill roller 1 being supported rotatably at theopposite end of the moment arm.

Means for applying a force to the moment arm 5 are further provided inorder to adjust the pressure which is applied by the mill roller. Thosemeans comprise a pressure cylinder 7 which is arranged so as to be fixedin position and which acts on the moment arm 5 substantiallyperpendicularly relative to the connection line between the bearing 6and the mill roller 1. The pressure cylinder 7 is preferably formed by aplunger cylinder. A contact location 8, at which the force of thepressure cylinder 7 is transmitted to the moment arm 5, is locatedoutside the mill inner space 4.

In the embodiment illustrated, the pressure cylinder 7 acts in a centralregion between the mill roller 1 and the bearing 6 on the moment arm 5.In the context of the invention, however, it would also be conceivablefor the positions of the bearing and pressure cylinder to be transposed.

The moment arm 5 in the embodiment illustrated is further constructed soas to be rectilinear, but non-linear moment arms are also conceivable inprinciple.

The bearing 6 is preferably formed by an axial spherical plain bearing,there being used in particular two axial spherical plain bearings whichare arranged opposite each other and which can be tensioned relative toeach other, whereby the bearing play can be minimised. The mill roller 1at the other end of the moment arm 5 is supported by means of twotapered roller bearings 9 which are mounted in an O-like arrangement, alubricant space 10 of the tapered roller bearings 9 extending as far asa region outside the mill inner space 4 and being sealed at thatlocation.

As is visible in the schematic illustration of FIG. 2, the bearing 6allows a pivoting movement of the moment arm 5 through an angle α.Consequently, there is produced a relative movement between the fixedpressure cylinder 7 and the moment arm 5.

Since the pressure cylinder 7 is in constant operative contact with themoment arm 5, therefore, transverse forces are produced in the region ofthe contact location owing to the relative movement. In order tocompensate for the relative movement between the pressure cylinder 7 andthe moment arm 5, there is provided a pressure bearing 10 which allowsrelative movement between the pressure cylinder and the moment arm. Thepressure bearing is illustrated in greater detail in FIG. 3 and has afirst pressure face 10 a and a second pressure face 10 b in order toapply a sliding movement, a friction coefficient which is less than 0.2being provided by the sliding pair being selected in a suitable manner.In order to further reduce the transmission of the transverse forces tothe cylinder 7, there is further provided a third and a fourth slidingface for applying a pivoting movement. The friction coefficient can alsobe minimised in this instance by means of suitable sliding pairs. InFIG. 3, the central position of the moment arm is illustrated with solidlines and the two extreme positions of the moment arm in connection withthe pressure bearing are illustrated with broken lines.

With this construction of the pressure bearing, the force transmissionfrom the pressure cylinder to the moment arm can be carried out in avery compact manner.

It has further been found during attempts forming the basis of theinvention that the relationship of the distance a between the pressurecylinder 7 and the mill roller 1 to the distance b between the pressurecylinder 7 and the bearing 6 should be in the order of 1:0.9 and 1:1.2,preferably in the order of 1:1.0 and 1:1.1, in order to minimise to thegreatest possible extent the forces which act in the bearing 6, thepressure cylinder 7 and the corresponding counter-bearings.Corresponding reductions in weight are thereby possible in the elementsinvolved.

1. Roller mill having at least one mill roller (1) and a rotatable millplaten (2), which are arranged in a mill inner space (4), and a momentarm (5) which is retained so as to be pivotably movable and rotationallysecure in a bearing (6), with the mill roller (1) being supported in arotatable manner at one end of the moment arm and there further beingprovided means for applying a force to the moment arm which are inoperative contact with the moment arm in order to adjust the pressurewhich is applied by the mill roller, the contact location (8), at whichthe force is transmitted to the moment arm (5) being located outside themill inner space (4), wherein the means for applying the force to themoment arm comprise a pressure cylinder (7) which is in operativecontact with the moment arm in order to adjust the pressure applied bythe mill roller, and in that there is provided between the pressurecylinder and the moment arm (5) at least one pressure bearing (10) whichallows relative movement between the pressure cylinder (7) and themoment arm (5).
 2. Roller mill according to claim 1, characterised inthat the pressure cylinder (7) acts on the moment arm (5) in a centralregion between the mill roller (1) and the bearing (6).
 3. (canceled) 4.Roller mill according to claim 1, characterised in that the pressurebearing (10) has a first and a second pressure face (10 a, 10 b) inorder to apply a sliding movement and a third and a fourth pressure face(10 c, 10 d) in order to apply a pivoting movement.
 5. Roller millaccording to claim 1, characterised in that the pressure bearing (10)has a first and a second pressure face (10 a, 10 b) in order to whichallows a sliding movement with a friction coefficient which is less than0.2.
 6. Roller mill according to claim 1, characterised in that thepressure cylinder (7) is arranged so as to be fixed in position. 7.Roller mill according to claim 1, characterised in that the pressurecylinder (7) is orientated perpendicularly relative to the connectionbetween the bearing (6) and the mill roller (1).
 8. Roller millaccording to claim 1, characterised in that the bearing (6) of themoment arm (5) is formed by an axial spherical plain bearing.
 9. Rollermill according to claim 1, characterized characterised in that themoment arm (5) is constructed so as to be rectilinear.
 10. Roller millaccording to claim 1, characterised in that the pressure cylinder (7) isformed by a plunger cylinder.
 11. Roller mill according to claim 1,characterised in that the relationship of the distance (a) between thepressure cylinder (7) and the milling roller (1) to the distance (b)between the pressure cylinder (7) and the bearing (6) of the moment arm(5) is in the order of 1:0.9 and 1:1.2, preferably in the order of 1:1.0and 1:1.1.